Diet and coronary heart disease--a review

Few topics have aroused more scientific controversy than the relationship of diet and coronary heart disease (CHD), yet it is still not fully resolved largely due to the difficulties in measuring diet, particularly over a long-term period. Studies have established that low density lipoprotein cholesterol (LDL-C) is a major risk factor for CHD and that a diet, high in saturated fatty acids (SFAs) and cholesterol and low in polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs) increases LDL-C. However, the evidence directly linking dietary lipids and CHD is less definite. In particular, trials on dietary change have been inconclusive with some showing no effect and others some benefits. Marine PUFAs have been found in some studies to be associated with reduced CHD mortality. Antioxidants (e.g. vitamins E and C) reduce oxidation of LDL and hence possibly atherosclerosis and some studies have shown their protective effect. There is some evidence that high dietary fibre is associated with lower CHD risk but there has been no real evidence as yet, for a similar effect for minerals. Moderate alcohol intake is protective. It is recommended that total fat intake should not constitute more than 30% of calories (approximately equally divided between SFAs, PUFAs and MUFAs) and cholesterol intake not more than 300 mg per day (similar to the United States National Cholesterol Education Program Step I Diet). Regular fatty fish consumption and a high intake of fresh fruits and vegetables is recommended. For persons with high LDL-C and particularly also with CHD, the Step II Diet is recommended.